The present invention relates generally to apparatus for carrying cargo and more particularly to backpacks adaptable for use on extended hiking or camping expeditions.
Backpacks of various designs and configurations are commonly used by hikers, campers and others to carry cargo on their backs or shoulders for extended distances. Because the center of gravity of the loaded backpack is a spaced distance behind the wearer's body, the force of gravity acting through the center of gravity of the cargo in combination with the upwardly directed supporting force exerted by the wearer's shoulders creates a force couple tending to rotate the wearer's shoulders backward and downward. In order to maintain an upright posture, this couple must be resisted primarily by the wearer's lower back. The application of these forces to the wearer's lower back over extended periods of time often results in fatigue and possible injury to the back. The stress of the shoulder strap on the collarbone from a conventional backpack which compresses the upper trunk of the brachial plexus against the underlying rib cage is also believed to be a primary cause of pack pulsy which has a high rate of occurrence among backpackers.
Several attempts have been made to alleviate these problems caused by common backpacks. The U.S. Pat. No. 2,208,962 issued to G. DeFinetti and the Italian Pat. No. 380,036 issued to P. Spalla, both disclose rigid levers extending forwardly over the wearer's shoulders from a rigid backpack frame and have widened or padded shoulder pads. While these innovations are partially effective to relieve some of the problems caused by conventional backpacks, they also have certain disadvantages. The apparatus of the present invention is designed to more effectively shift the load to the person's shoulders and arms and away from his upper chest and lower back, as well as to provide more convenience, flexibility, safety, and ease of use.